The present invention relates to pyrogenic oxides and a process for their preparation and to their use as polishing agents.
It is known to prepare pyrogenic silicon dioxide and also other metal- or metalloid oxides by means of high-temperature flame hydrolysis; see Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, volume 21 pages 464 et seq.
In the known process, metal and/or metalloid halide compounds, such as, for example, silicon halide compounds or organosilicon halide compounds, are mixed and burned together with atmospheric oxygen and hydrogen in a burner of known design. The pyrogenic silica formed is then separated off from the gases containing hydrogen chloride, and any chloride still adhering to the oxide is removed by treatment with air containing water vapor.
The known oxides, however, exhibit the disadvantage that their polishing performance is too low when used for CMP polishing.
There is therefore an object of the present invention to avoid the problems of the prior art and to develop a pyrogenically prepared oxide having an improved polishing performance.